US6937310B2ExpiredUtilityPatentIndex 92

Compensation films for LCDs

Assignee: EASTMAN KODAK COPriority: May 16, 2003Filed: May 16, 2003Granted: Aug 30, 2005

Est. expiryMay 16, 2023(expired)· nominal 20-yr term from priority

Inventors:ELMAN JAMES F ISHIKAWA TOMOHIRO MASSA DENNIS J YACOBUCCI PAUL D FALKNER CATHERINE A

G02F 2202/022C08L 67/03C08G 63/193G02F 1/133634C08J 2367/03G02B 5/3083C08L 2203/16G02F 1/133637C09K 2323/03

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Claims

Abstract

Disclosed is an optical compensation film for Liquid Crystal Displays comprising an amorphous polymer layer disposed on a substrate wherein said amorphous polymer layer has an out-of-plane birefringence Δn th (λ) at a wavelength λ that satisfies both conditions (1) and (2): Condition (1) Δn th (λ) is more negative than −0.005 throughout the range of 370 nm<λ<700 nm; Condition (2) Δn th (λ 1 ) is more negative than Δn th (λ 2 ), for λ 1 <λ 2 throughout the range of 370 nm<λ<700 nm.

Claims

exact text as granted — not AI-modified

1. An optically transparent compensation film for Liquid Crystal Displays comprising an amorphous polymer layer disposed on a substrate wherein said amorphous polymer layer comprises a polymer with a glass transition temperature Tg above 180° C. and has an out-of-plane birefringence Δn th (λ) at a wavelength λ that satisfies both conditions (1) and (2):
 Condition (1)  
 
       Δn th (λ) is more negative than −0.005 throughout the range of 370 nm&lt;λ&lt;700 nm; 
 Condition (2)  
 
       Δn th (λ 1 ) is more negative than Δn th (λ 2 ), for λ 1 &lt;λ 2  throughout the range of 370 nm&lt;λ&lt;700 nm.  
     
     
       2. An optically transparent compensation film according to  claim 1  wherein, the out-of-plane phase retardation, R th , of said compensation film satisfies condition (3):
 Condition (3)  
 
       R th  at λ 1  is more negative than R th  at λ 2 , for λ 1 &lt;λ 2  throughout the range of 400 nm&lt;λ&lt;700 nm.  
     
     
       3. An optically transparent compensation film according to  claim 2  wherein, said amorphous polymer layer is contiguous to the substrate. 
     
     
       4. An optically transparent compensation film according to  claim 2  wherein, said amorphous polymer layer is contiguous to a barrier layer, which is contiguous to the substrate. 
     
     
       5. An optically transparent compensation film according to  claim 2  wherein, said substrate is optically uniaxial. 
     
     
       6. An optically transparent compensation film according to  claim 5  wherein, said uniaxial substrate is negative-C plate and the R th (at λ=550 nm wavelength) is between −20 to −250 nm. 
     
     
       7. An optically transparent compensation film according to  claim 2  wherein, said substrate is optically biaxial. 
     
     
       8. An optically transparent compensation film according to  claim 2  wherein, an additional layer is disposed on said amorphous polymer layer. 
     
     
       9. An optically transparent compensation film according to  claim 8  wherein, said additional layer has an anti-reflection function. 
     
     
       10. An optically transparent compensation film according to  claim 8  wherein, said additional layer has an anti-glare function. 
     
     
       11. An optically transparent compensation film according to  claim 8  wherein, said additional layer is a hard-coat layer. 
     
     
       12. An optically transparent compensation film according to  claim 2  wherein, said substrate is optically isotropic. 
     
     
       13. An optically transparent compensation film according to  claim 2  wherein, said amorphous polymer layer has a thickness of from 0.1 to 30 μm. 
     
     
       14. An optically transparent compensation film according to  claim 13  wherein, said amorphous polymer layer has a thickness of from 1 to 10 μm. 
     
     
       15. An optically transparent compensation film according to  claim 2  wherein, said amorphous polymer layer comprises a polymer containing in the backbone a non-visible chromophore group. 
     
     
       16. An optically transparent compensation film according to  claim 15  wherein, said non-visible chromophore group includes a carbonyl, amide, ester, carbonate, phenyl, naphthyl, biphenyl, bisphenol, or thiophene group. 
     
     
       17. An optically transparent compensation film of  claim 15  wherein, said amorphous polymer layer comprises a polymer containing in the backbone a non-visible chromophore group that does not contain a chromophore off of the backbone. 
     
     
       18. An optically transparent compensation film according to  claim 17  wherein, said amorphous polymer layer comprises a polymer containing in the backbone a vinyl, carbonyl, amide, ester, carbonate, aromatic, sulfone, or azo group. 
     
     
       19. An optically transparent compensation film according to  claim 2  wherein, said amorphous polymer layer comprises 1)poly(4,4′-hexafluoroisopropylidene-bisphenol) terephthalate-co-isophthalate, 2)poly(4,4′-hexahydro-4,7-methanoindan-5-ylidene bisphenol) terephthalate, 3) poly(4,4′-isopropylidene-2,2′6,6′-tetrachlorobisphenol) terephthalate-co-isophthalate, 4) poly(4,4′-hexafluoroisopropylidene)-bisphenol-co-(2-norbornylidene)-bisphenol terephthalate, 5) poly(4,4′-hexahydro-4,7-methanoindan-5-ylidene)-bisphenol-co-(4,4′-isopropylidene-2,2′,6,6′-tetrabromo)-bisphenol terephthalate, or 6) poly(4,4′-isopropylidene-bisphenol-co-4,4′-(2-norbornylidene) bisphenol) terephthalate-co-isophthalate or copolymers of any of the foregoing. 
     
     
       20. An optically transparent compensation film according to  claim 2  wherein, said amorphous polymer layer comprises poly(4,4′-hexafluoroisopropylidene-bisphenol-co-4,4′-(2-norbornylidene) bisphenol) terephthalate-co-isophthalate or copolymers thereof. 
     
     
       21. An optically transparent compensation film according to  claim 2  wherein, said substrate comprises triacetylcellulose (TAC), polycarbonate, cyclic polyolefin or polyarylate containing fluorene groups. 
     
     
       22. An optically transparent compensation film according to  claim 2  wherein, more than one layer of said amorphous polymer are disposed on said substrate. 
     
     
       23. An optically transparent compensation film according to  claim 2  wherein, the thickness of said compensation film is less than 115 μm. 
     
     
       24. An optically transparent compensation film according to  claim 24  wherein, the thickness of said compensation film is between 40 to 100 μm. 
     
     
       25. A liquid crystal display comprising a liquid crystal cell, a pair of crossed polarizers located one on each side of the cell, and at least one optical compensation film according to  claim 2 . 
     
     
       26. A liquid crystal display according to  claim 25  wherein, said liquid crystal cell is a Vertically Aligned liquid crystal cell or Twisted Nematic liquid crystal cell. 
     
     
       27. A process for forming an optically transparent compensation film for an liquid crystal displays comprising coating an layer of amorphous polymer in a solvent onto a substrate wherein, said amorphous polymer layer satisfies the both conditions (1) and (2):
 Condition (1)  
 
       Δn th (λ) is more negative than −0.005 throughout the range of 370 nm&lt;λ&lt;700 nm; 
 Condition (2)  
 
       Δn th (λ 1 ) is more negative than Δn th (λ 2 ), for λ 1 &lt;λ 2  throughout the range of 370 nm&lt;λ&lt;700 nm, 
       and said amorphous polymer layer comprises selected polymeric materials and said layer has sufficient thickness so that the out-of-plane retardation R th (at λ=550 nm wavelength) of said amorphous polymer layers is more negative than −5 nm. 
     
     
       28. An optical compensation film for Liquid Crystal Displays comprising an amorphous polymer layer disposed on a polymeric substrate wherein said amorphous polymer layer comprises a polymer with a Tg above 180° C. and has an out-of-plan birefringence Δn th (λ) at a wavelength λ that satisfies both conditions (1) and (2):
 Condition (1)  
 
       Δn th (λ) is more negative than −0.005 throughout the range of 370 nm&lt;λ&lt;700 nm; 
 Condition (2)  
 
       Δn th (λ 1 ) is more negative than Δn th (λ 2 ), for λ 1 &lt;λ 2  throughout the range of 370 nm&lt;λ&lt;700 nm.  
     
     
       29. An optical compensation film according to  claim 28  wherein, said polymeric substrate comprises triacetylcellulose (TAC), polycarbonate, cyclic polyolefin or polyarylate containing fluorene groups. 
     
     
       30. An optical compensation film according to  claim 28  wherein, said amorphous polymer layer comprises 1)poly(4,4′- hexafluoroisopropylidene-bisphenol) terephthalate-co-isophthalate, 2)poly(4,4′- hexahydro-4,7-methanoindan-5-ylidene bisphenol) terephthalate, 3) poly(4,4′- isopropylidene-2,2′6,6′-tetrachlorobisphenol) terephthalate-co-isophthalate, 4) poly(4,4′-hexafluoroisopropylidene)bisphenol-co-(2-norbornylidene)-bisphenol terephthalate, 5) poly(4,4′-hexahydro-4,7-methanoindan-5-ylidene)-bisphenol-co- (4,4′-isopropylidene-2,2′,6,6′-tetrabromo)-bisphenol terephthalate, or 6) poly(4,4′-isopropylidene-bisphenol-co-4,4′-(2-norbornylidene) bisphenol) terephthalate-co-isophthalate or copolymers of any of the foregoing. 
     
     
       31. An optical compensation film according to  claim 28  wherein, said amorphous polymer layer comprises poly(4,4′-hexafluoroisopropylidene-bisphenol-co-4,4′-(2-norbornylidene) bisphenol) terephthalate-co-isophthalate or copolymers thereof. 
     
     
       32. An optical compensation film according to  claim 28  wherein, said amorphous polymer layer comprises a polymer containing in the backbone a nopn-visible chromophore group. 
     
     
       33. A liquid crystal display comprising a liquid crystal cell, a pair of crossed polarizers located one on each side of the cell, and a least one optical compensation film according to  claim 28 . 
     
     
       34. A liquid crystal display according to  claim 33  wherein, said liquid crystal cell is a Vertically Aligned liquid crystal cell or Twisted Nematic liquid crystal cell.

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